Search for gamma gamma decays of a Higgs boson produced in association with a fermion pair in e(+)e(-) collisions at LEP

摘要

A search for yy decays of a Higgs boson is performed in the data sample collected at LEP with the ALEPH detector between 1991 and 1999. This corresponds to an integrated luminosity of 672pb(-1) at centre-of-mass energies ranging from 88 to 202 GeV. The search is based on topologies arising from a Higgs boson produced in association with a fermion pair via the Higgs-strahlung process e(+)e(-)--> Hf (f) over bar with f (f) over bar = nu<(nu)over bar>, e(+)e(-), mu(+)mu(-),tau(+)tau(-) or q (q) over bar. Twenty-two events are selected in the data, while 28 events are expected from standard model processes. An upper limit is derived, as a function of the Higgs boson mass, on the product of the e(+)e(-)--> Hf (f) over bar: cross section and the H --> gamma gamma branching fraction. In particular, a fermiophobic Higgs boson produced with the standard model cross section is excluded at 95% confidence level for all masses below 100.7 GeV/c(2). (C) 2000 Elsevier Science B.V. All rights reserved. [References: 25]